Limber Pine (Pinus flexilis James), a Flexible Generalist of Forest Communities in the Intermountain West.

Marcella A Windmuller-Campione,James N Long,Daniel Doucet

doi:10.1371/journal.pone.0160324

Marcella A Windmuller-Campione, James N Long + Show 1 more

Open Access

https://doi.org/10.1371/journal.pone.0160324

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Abstract

As forest communities continue to experience interactions between climate change and shifting disturbance regimes, there is an increased need to link ecological understanding to applied management. Limber pine (Pinus flexilis James.), an understudied species of western North America, has been documented to dominate harsh environments and thought to be competitively excluded from mesic environments. An observational study was conducted using the Forest Inventory and Analysis Database (FIAD) to test the competitive exclusion hypothesis across a broad elevational and geographic area within the Intermountain West, USA. We anticipated that competitive exclusion would result in limber pine’s absence from mid-elevation forest communities, creating a bi-modal distribution. Using the FIAD database, limber pine was observed to occur with 22 different overstory species, which represents a surprising number of the woody, overstory species commonly observed in the Intermountain West. There were no biologically significant relationships between measures of annual precipitation, annual temperature, or climatic indices (i.e. Ombrothermic Index) and limber pine dominance. Limber pine was observed to be a consistent component of forest communities across elevation classes. Of the plots that contained limber pine regeneration, nearly half did not have a live or dead limber pine in the overstory. However, limber pine regeneration was greater in plots with higher limber pine basal area and higher average annual precipitation. Our results suggest limber pine is an important habitat generalist, playing more than one functional role in forest communities. Generalists, like limber pine, may be increasingly important, as managers are challenged to build resistance and resilience to future conditions in western forests. Additional research is needed to understand how different silvicultural systems can be used to maintain multi-species forest communities.

Highlights

Forest research was primarily focused on commercially productive species or forest communities [1]
Across the Intermountain West, overstory limber pine was observed across a wide range of environmental conditions and a broad geographic area (Table 1; Fig 1)
Limber pine was observed to occur with twenty-two different overstory species and was observed, on average, to be a consistent component in the overstory across broad elevational classes when present on Forest Inventory and Analysis (FIA) plots (Fig 3)

Summary

Introduction

Forest research was primarily focused on commercially productive species or forest communities [1]. There is still relatively limited information on the forest dynamics of non-commercial systems An example of these systems includes the high elevation, five-needle white pine species (the high five) of the middle latitudes of western North America. The “high five” includes six species of five-needle white pines, belonging to the Family Pinaceae, Genus Pinus and the subgenus Strobus [3]. They have been grouped together because of morphological and ecological similarities [4]. They provide valuable wildlife habitat [6], serve as a wildlife food source [7], [8], influence snow dynamics and the timing of run-off [9], and serve as important symbols of strength and endurance for mountain visitors [10]

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